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Does a passive crystal oscillator have a direction?
A passive crystal oscillator has no direction, and the pins of a passive crystal oscillator do not distinguish between positive and negative poles.
How do you identify the direction of a passive crystal oscillator? Will there be any problem if the passive crystal oscillator is pasted upside down?
First of all, it is necessary to clarify that crystal oscillators are divided into two categories: passive crystal oscillators and active crystal oscillators. The English name of a passive crystal oscillator is Crystal, and its full name in Chinese is quartz crystal resonator. Some people also like to call passive crystal oscillators crystals. The English name of an active crystal oscillator is Oscillator, and its full name in Chinese is quartz crystal oscillator, also known as clock oscillator, and some people directly call it OSC.
Two-pin passive crystal oscillator: one pin is the frequency output pin, and the other pin is the frequency input pin. Even if it is reversed, the crystal oscillator still works normally.
Four-pin patch passive crystal oscillator: Generally, pins 1 and 3 are the frequency input pins and frequency output pins, and the other two pins (pins 2 and 4) are ground pins. Even if it is rotated 180 degrees, only pin 1 and pin 3 are swapped, that is, the input pin becomes the output pin, and the output pin becomes the input pin. The crystal oscillator can still work normally, and there will be no performance and function differences.
| 脚位注释 | |
| 1脚 | In/Out |
| 2脚 | GND |
| 3脚 | In/Out |
| 4脚 | GND |
Active crystal oscillators have directionality, and they will be damaged by current if they are attached upside down. Passive crystal oscillators have no directionality, and it doesn't matter if they are attached upside down. In other words: whether the passive crystal oscillator is plug-in type or SMD type, or has two or four pins, there is no distinction between positive and negative poles, and no directionality when attaching or welding, so don't worry about attaching it upside down.
